Wynne said the Liberals plan to introduce legislation next week, that, if passed, would ensure that no Ontario station will burn coal again.
The Ending Coal for Cleaner Air Act would ensure that coal facilities stop operating by the end of 2014, Wynne said.
Over the next year, Thunder Bay Generating Station will stop burning coal and will be converted to use advanced biomass, a fuel for electricity generation. This is the last major step in Ontario's plan to eliminate coal-fired electricity.
"Becoming a coal-free province is the equivalent of taking up to seven million cars off the road, which means we'll have cleaner air to breathe, while saving Ontario $4.4 billion in health, financial and environmental costs," Wynne said.
She made the announcement in Toronto alongside former U.S. vice-president and environmental activist Al Gore.
"Ontario has become the first regional jurisdiction in all of North America to take these steps to ban the burning of coal," Gore said.
"Congratulations Ontario, and thank you, Ontario," Gore added.
The Liberals still need the support of at least one of the opposition parties for the legislation to pass.
An Ontario-based environmental group lauded Wynne's announcement.
"Ontario has shown the world that bold action on climate change can be done," said Tim Gray of Environmental Defence.
"Ontarians should feel proud to live in the first jurisdiction in North America that is kicking the coal habit, and we hope others follow this lead," Gray said.
The government said Ontario's elimination of coal-fired electricity is the single largest greenhouse gas reduction initiative in North America.
And it said early coal closure at Lambton and Nanticoke will save the province's electricity customers about $95 million through reduced operating and maintenance costs.